Title: Ferronickel slag produced in New Caledonia: characterisation and carbonation in seawater

Authors: Jordan Prévot; Arnaud Serres; Peggy Gunkel-Grillon; René Sabot; Marc Jeannin

Addresses: Laboratoire des Sciences Exactes et Appliquées (ISEA EA7584), Université de la Nouvelle-Calédonie, BP R4, 98851 Nouméa Cedex, New Caledonia ' Laboratoire des Sciences Exactes et Appliquées (ISEA EA7584), Université de la Nouvelle-Calédonie, BP R4, 98851 Nouméa Cedex, New Caledonia; Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE UMR CNRS 7356), Pôle Sciences et Technologie, La Rochelle Université, Avenue Michel Crépeau, 17042 La Rochelle Cedex 1, France ' Laboratoire des Sciences Exactes et Appliquées (ISEA EA7584), Université de la Nouvelle-Calédonie, BP R4, 98851 Nouméa Cedex, New Caledonia ' Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE UMR CNRS 7356), Pôle Sciences et Technologie, La Rochelle Université, Avenue Michel Crépeau, 17042 La Rochelle Cedex 1, France ' Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE UMR CNRS 7356), Pôle Sciences et Technologie, La Rochelle Université, Avenue Michel Crépeau, 17042 La Rochelle Cedex 1, France

Abstract: Ferronickel slags (FNS) have been studied for a potential use of this industrial waste in seawater through mineral carbonation. Leaching tests have been performed using seawater and EDTA, a strong chelating agent. In both cases, only small concentrations (in the range of µg/g) of released heavy metals are measured by inductively coupled plasma, demonstrating the non-hazardousness of FNS. The carbonation process of FNS was then observed by immersing them in artificial and natural seawater tanks for respectively four and seven months. FNS surface and cross-section samples have then been observed by scanning electron microscopy and chemical analysis. After seven months, a 5 cm thick sturdy conglomerate, composed of FNS stuck by a 25 µm thick calcium carbonate layer, is obtained. A mechanism of this natural carbonation process is proposed in the light of CO₂ sequestration.

Keywords: ferronickel slags; FNS; mineral carbonation; waste valorisation; metals leaching; CO₂ sequestration; New Caledonia.

DOI: 10.1504/IJMME.2022.124148

International Journal of Mining and Mineral Engineering, 2022 Vol.13 No.1, pp.76 - 91

Accepted: 18 Apr 2022
Published online: 14 Jul 2022 *